The present invention is related to reciprocating machines, and particularly to an air valve actuator for reciprocating machines. The invention is particularly adaptable for use in connection with double-acting pneumatic reciprocating diaphragm pumps and the like, wherein a pair of spaced apart diaphragm pumping chambers are interconnected by a common shaft. The invention may also find use as a pilot valve in certain industrial applications, to divert a source of pressurized fluid to either of several paths as a result of sensing a relatively small range of mechanical movement.
Reciprocating machines, and in particular reciprocating motor and pump mechanisms, utilize a valving apparatus for controlling the stroke and the reversing mechanisms to permit the reciprocating action to occur. Such machines typically use a reversing valve which is actuated by the reciprocating mechanism near the end of a stroke, to switch the driving force acting against a piston and/or diaphragm from one direction to the opposite direction. In the case of double-acting pumps, the valve reversing mechanism is utilized to exhaust the driving fluid from one side of the pump, and to admit the driving fluid into the other side of the pump. In most cases double-acting, reciprocating pumps are constructed with the active pumping elements arranged along a common axis, and with a common shaft interconnecting both elements. The common shaft therefore reciprocates in accordance with the driving elements, which may be pistons or diaphragm elements. The reversing mechanism is conveniently coupled to the reciprocable common shaft to sense the stroke position, and to actuate a reversing valve at an appropriate stroke position, to divert the pressurized driving fluid from one side of the pump to the other.
The valve actuator which causes this fluid flow diversion must be capable of positive action over a wide range of reciprocating speeds. At extremely slow reciprocating speeds the valve actuator must not be susceptible to unstable or incomplete actuation, for this could cause the pump to "stall" and cease operating. At extremely high reciprocating speeds the valve actuator must be capable of actuation very quickly in order to enable the pump to deliver the necessary and required liquid flow rates. The slow speed requirements dictate a valve actuator which has positive, snap-action operation at the changeover point. The high-speed requirement dictates that the valve actuator have relatively low mass and inertia.
It is therefore a principal object of the present invention to provide an actuator for reciprocable machines which is capable of positive and reliable actuation over a wide range of operating speeds.
It is a further object of the present invention to provide a reciprocating machine valve actuator which has a positive action at a predetermined position of the reciprocating machine, regardless of speed of operation.
It is another object of the present invention to provide an air valve actuator for a double-acting diaphragm pump which is of simple and reliable construction.
It is yet a further object of the present invention to provide an air valve actuator for a double-acting reciprocable pump which operates as an inexpensive and simple reversing valve.
The foregoing and other objects will become apparent from the specification and claims herein, and with reference to the accompanying drawings. It should be understood, however, that the detailed description and the accompanying drawings, while indicating preferred embodiments of the present invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art. Such changes and modifications should be considered to be within the scope of this invention.